1. Field of the Invention
The present invention relates to a hollow body for use as seat pad having a resting region, a sitting region, and a transition region arranged between them.
2. Description of the Prior Art
In general, seat pads are known which are developed in the form of cushions (seat cushions). These seat pads are, on the one hand, filled with elastic or resilient filling material, for instance springs, foam, or the like, and, on the other hand, are developed as air cushions, the stiffness of the seat pad being obtained by a volume of gas enclosed in the seat pad.
These known seat pads, however, lead to a sitting position which is ergonomically incorrect and to continuous improper stressing of the body. Cramps, tenseness or even permanent damage to health (for instance, curvature of the spine) can be caused thereby.
On the other hand, it is known that seat balls result in an ergonomically advantageous sitting position in that the body is induced to effect continuous movements of equalization (so-called "dynamic sitting").
Due to their shape, such seat balls require a support or holding structure so that they do not roll away. Government institutions, for instance schools, have prohibited the use of such seat balls in areas accessible to the public, in particular because of the danger of their rolling away. If a backrest for the seat is desired, the holding structure is more elaborate and thus more expensive.